DE3626286A1 - MAGNETIC TAPE CASSETTE - Google Patents

Description

The invention relates to a magnetic tape cassette, in particular a compact cassette of the Philips type, which has a front side opening for the device-side head and one Device for pressing the magnetic tape onto the head owns.

In a cassette of this type, which is shown in Fig. 1, for sound recording and playback, the (not ge) taped head through the opening ( 2 ) on the magnetic tape ( 3 ), which from the other side by a pressure spring ( 4 ), which carries a cushion ( 5 ) on its front, is pressed against the sound head. In this way, close contact between the tape head and the magnetic tape is achieved. To rewind the magnetic tape, the tape head is swung out, so that the magnetic tape itself is only on the tape guide elements present on the front of the cassette, namely the rollers ( 6 , 6 ') and the webs ( 7 , 7 ') and the pins ( 8 , 8 ′) is guided and should pass freely through the middle opening. However, in many cases len when rewinding an unwanted contact of the magnetic netband with the pressure pad occurs, which increases the rewinding torque and can also cause annoying noises. The reasons can be:

• - The pressure spring is mounted on most compact cassettes on both sides of the front middle opening between the tape guide pins ( 8 , 8 ') and the abutments ( 9 , 9 '). These abutments can be webs extending from the head chamber ( FIG. 1) or, in other constructions, the bent ends of the shielding plate ( FIG. 2) or molded pins ( FIG. 3). For spritztechni reasons, the distance between tape guide pins and abutment must have a minimum value of about 0.5 mm, which means that the pressure spring has a certain bearing play and can thus touch the magnetic tape via the pressure pad.
• - The pressure pad, which is generally made of a felt exists, due to the cassette specifications have a certain thickness. Because of production tolerances in the thickness of the felt and because of the fact that from hair can protrude from the felt when rewinding There are possibilities to touch the tape.

According to the teaching of DE-OS 22 16 769, this is said Problem can be solved by putting the magnetic tape in the Pass-through openings for the sound head or the sound heads Spring arms are held at a distance, which are fixed together connected and tilting by means of a common joint are held in the cassette housing. With the so formed Cassette is inserted by pushing the tape heads into the through handle openings the magnetic tape applied to the spring arms and held by these permanently on the heads, whereby different depths of immersion of the heads by swiveling ken of the spring arms are compensated for, while missing Active connections between magnetic tape and tape heads to the accessory When rewinding, play the magnetic tape smoothly above the spring arms are running. The construction described is rela tiv complicated and therefore expensive to manufacture,  so they're for a bulk item like a compact cassette seems too expensive.

From DE-OS 28535 459 is a resilient shielding element known for magnetic tape cassettes, which in the relaxed state is already curved, but with this construction tion the above-mentioned disadvantage of the camp game and also the resilient element has a relatively compli? graced material composition or a compli graced structure.

The present invention was based on the object To create a magnetic tape cassette of the type mentioned at the beginning, which avoids the disadvantage mentioned and is also simple is to be produced.

The object was achieved with a magnet tape cassette with in the characterizing part of the claim 1 mentioned features. Further details can be found in the Subclaims, the description and the drawings in front.

The invention will now be explained in more detail with reference to the drawings tert shows:

Fig. 1 is a plan view of a cassette corresponding to the prior art

FIGS. 2 and 3 enlarged sections of FIG. 1 with conventional bearings of the pressure device

Fig. 4 shows an enlarged section of the front of the cassette with a particularly preferred embodiment of the invention.

The inventive idea was to bias the pressure spring ( 4 ) so that the above-mentioned bearing play is eliminated and the pressure pad is shifted slightly towards the inside of the cassette, so that, as can be seen from FIG. 2, there is no tape contact with the pad during the rewinding process can come. This is achieved by immediately adjacent to the tape guide pins ( 8 , 8 ') and the abutment ( 9 , 9 ') preferably in the direction of the central opening ( 2 ) of the front cassette part two posts ( 11 , 11, ) so attached are that the pressure spring ( 4 ) with the pillow ( 5 ) between the posts is either flat or in Rich direction to the shielding plate ( 10 ) is slightly bent. In a preferred embodiment, the posts on the webs ( 12 , 12 ') of the bottom part ( 1 ), which cause the height of the pressure spring tion, are injection molded. As a result, only an insignificant change in the injection mold is necessary for the production of the cassette base part.

The bearing elements ( 8 , 8 '), ( 9 , 9 ') and ( 11 , 11 ') can have an insertion bevel from above for easier insertion of the pressure spring by being chamfered in the upper part.

Preferably, the front, the magnetic tape facing surfaces ( 13 , 13 ') of the post not parallel to the plane of the magnetic tape, but beveled trapezoidal towards the cassette interior, so that when the sound head is swung in there is no danger that the magnetic tape on one edge of the post scrubs.

In addition to the simple construction, the solution according to the invention tion still the additional advantage that in the assembly of the compact cassette, as it is pre- is tight, stuck in the bottom part after insertion and therefore not during the manufacturing process connected transport processes can fall out.

Claims (4)

1. Magnetic tape cassette, consisting of a base and a cover part, an interior containing the tape wrap, a front opening for a device-side sound head, a pressure device that has a cushion and a cushion holding the one-piece leaf spring, which pin the opening between the tape guides on both sides and underlying abutments is pluggable GE, characterized in that immediately be adjacent to the tape guide pins ( 8 , 8 ') and the abutment ( 9 , 9 ') two posts ( 11 , 11 ') are attached, which are positioned so that the Leaf spring ( 4 ) rests with its front against the post and with its back against the abutments and between the post is either flat or bent towards the inside of the cassette. 2. Magnetic tape cassette according to claim 1, characterized in that the posts ( 11 , 11 ') on webs ( 12 , 12 ') of the bottom part ( 1 ), which cause the height of the leaf spring ( 4 ), are injection molded. 3. Magnetic tape cassette according to claim 1-2, characterized in that the opening ( 2 ) facing surfaces ( 13 , 13 ') of the posts are tapered wedge-shaped to the center of the cassette. 4. A magnetic tape cassette according to claims 1-3, characterized in that the posts ( 11 , 11 ') and / or the abutment ( 9 , 9 ') and the tape guide pins ( 8 , 8 ') at their upper ends for the introduction of Leaf spring ( 4 ) are chamfered.